By State › Utah
Utah: Risks & Trends
Download all of Utah as PDF PrintThis page collects the same rigor and sourcing standard used throughout this section, applied to the state the rest of the site’s data already lives in: the Case for Preparedness document. Nothing below is new; it’s the Utah-specific figures from that document, gathered into the same format as every other state’s risks page.
The Wasatch Fault
| Metric | Figure | Source |
|---|---|---|
| Chance of M5.0+ quake, next 50 years | 93% | Working Group on Utah Earthquake Probabilities (UGS/USGS, 2016) |
| Chance of M6.0+ quake, next 50 years | 57% | Working Group on Utah Earthquake Probabilities |
| Chance of M6.75+ quake, next 50 years | 43% | Working Group on Utah Earthquake Probabilities |
| Population within 15 miles of the fault | ~85% of Utah's population, infrastructure, and economy | Working Group on Utah Earthquake Probabilities |
| Modeled fatalities, M7.0 event on the Salt Lake City segment | 2,000–2,750 | Earthquake Engineering Research Institute (Utah Chapter) / Utah Geological Survey, FEMA HAZUS methodology, 2015 |
| Modeled buildings destroyed outright | ~55,400 | Same HAZUS model |
| Modeled short-term direct economic loss | $33.2 billion | Same HAZUS model |
The probability and consequence figures above come from two separate studies, not one: the 93% (and related) probabilities are a forecast of how likely an earthquake of a given size is; the fatality and damage figures are a separate model of what a specific magnitude-7.0 event would do if it happened on the segment running beneath Salt Lake City specifically, the most populated part of the fault. See the full write-up for how the two studies fit together and what drives the projected death toll (largely unreinforced masonry buildings).
The 2020 Magna earthquake: a preview, not the event itself
| Metric | Figure |
|---|---|
| Magnitude | 5.7 |
| Deaths or serious injuries | 0 |
| Damage | $629 million |
| Households/businesses without power | ~50,000 |
| Aftershocks | 2,500+ |
Why nobody died
The quake hit at 7:09 a.m. on March 18, 2020, when Utah schools had just gone remote for COVID-19. A junior high school damaged badly enough to be declared a total loss would have had students inside on any normal school day. Utah’s own state seismologists have said Magna was ordinary background seismicity, a data point inside the Wasatch Fault forecast above, not evidence the larger risk has been released. Full write-up: Case for Preparedness.
The Great Salt Lake
| Metric | Figure |
|---|---|
| Wasatch Front residents exposed to lakebed dust | 2.5 million+ |
| Water lost from the lake annually | ~2 million acre-feet |
| Lowest recorded level | October 2022 (2025 water year: third-lowest on record) |
| Additional annual inflow needed to restore a healthy level by 2055 | 800,000 acre-feet, sustained |
Exposed lakebed contains arsenic, lead, and other heavy metals, linked by researchers to respiratory and cardiovascular health effects for the population living along the Wasatch Front. Full write-up: Case for Preparedness.
The 2026 Cottonwood Fire and the flood that followed it
| Metric | Figure |
|---|---|
| Acres burned | 97,464 (Utah's 6th-largest wildfire on record) |
| Structures destroyed | 150+ |
| Homes hit by the resulting flood, three weeks later | ~200 |
| Rainfall that triggered the flood | 1.5+ inches in 45 minutes, onto the fresh burn scar |
A debris flow off the burned mountainside tore out sections of State Route 153, shut down Interstate 15 for hours, and contaminated Beaver City’s municipal water supply. The fire and the flood were declared a single state of emergency, because a burned mountainside doesn’t stop being a hazard once the flames are out, it becomes a flood risk for months afterward instead. Full write-up: Case for Preparedness.
The mechanism behind both water crises: a shrinking, earlier-melting snowpack
Utah has no major river system of its own; both the Great Salt Lake and the state’s own share of the Colorado River system depend on mountain snowpack melting on a predictable schedule. That schedule is shifting: Utah’s peak mountain snowpack has declined 16% since 1979, and the date of peak snowpack now arrives about 9 days earlier than it used to, per NOAA and the Utah Climate Center at Utah State University. The same mechanism shows up at two different scales: the Great Salt Lake locally, and Lake Powell and Lake Mead at the river-basin scale Utah shares an allocation in alongside six other states.
Sources
- Wasatch Fault earthquake probabilities: Working Group on Utah Earthquake Probabilities (Utah Geological Survey / USGS, 2016)
- Magnitude-7.0 Salt Lake City segment loss modeling: Earthquake Engineering Research Institute, Utah Chapter, with Utah Geological Survey, using FEMA’s HAZUS methodology (2015)
- 2020 Magna earthquake damage and outage figures: Utah Geological Survey; contemporary reporting
- Great Salt Lake water level, health, and inflow-restoration figures: Utah Division of Water Resources; Great Salt Lake Strike Team
- 2026 Cottonwood Fire acreage, structures, and flood impact: Utah Division of Forestry, Fire and State Lands; Governor Spencer Cox’s state of emergency declaration
- Utah snowpack decline and peak-timing shift: NOAA; Utah Climate Center, Utah State University
- Full narrative and additional context for every figure above: Case for Preparedness